Intraoperative Spirometry during Reduction Pneumoplasty for Emphysema

Kim, Tae Sung

Abstract

BACKGROUND: Surgical resection of severely emphysematous lung tissue can significantly ameliorate shortness of breath, possibly by reducing dynamic airway compression and auto-PEEP. We utilized online spirometry to examine the intraoperative relationship between expiratory flow rate and compliance changes associated with a reduction pneumoplasty. METHODS: Eight surgical patients were anesthetized with IV propofol, isoflurane inhalation and thoracic epidural lidocaine/bupivacaine. A 37 or 39 left double lumen endobronchial tube (DLT) was placed and mechanical ventilation provided with tidal volume set at approximately 10 ml/kg. A Datex UltimaTM spirometer was placed at the proximal end of the DLT. Copies of flow/volume and pressure/volume curves (3 - 10 breaths) were obtained on a digital recorder during closed and open chest conditions, and before and after lung reduction. The mean +/- SD of expired tidal volume (VT), inspiratory plateau airway pressure (Pplat), respiratory rate, % of breath exhaled in 1 sec (V1.0%), and total dynamic compliance (CT) was measured. RESULTS: After a reduction pneumoplasty, CT decreased by an average 23% with open chest and 35% with closed chest conditions. Three subjects showed improved V1.0%, while 5 showed little change or reduced flow, hence no statistically significant change. There was no significant correlation between change in compliance and change in V1.0% (r2 = 0.24, p = 0.22). CONCLSIONS: An emphysematous reduction pneumoplasty reliably reduces lung compliance. However, reduced lung compliance did not reliably predict improved expiratory flow rates after a reduction pneumoplasty. The further reduction in CT with sternal closure may have been due to the return of dynamic airway compression.